In any mechanical walkway of those previously mentioned, several sections acting at different speeds are usually provided, such that following the direction of use thereof a first embarking area, a second slow speed area, an acceleration area, a larger maximum speed intermediate area, a deceleration area, a new slow speed area, and finally the disembarking area are established in said walkways.
In order to obtain the necessary variable speed in the acceleration and deceleration areas, there are various solutions among which the following must be pointed out:                A variable speed walkway formed by various rubber belts circulating at a constant speed. The rubber belts at the ends circulate at a slower speed, and the central rubber belt circulates at a faster speed, whereby a slower speed when embarking and disembarking is obtained. Walkways with these features are described in patent documents EP 0854108 A-1, EP 0850870 A-1 and EP 0773182 A-2.        A variable speed walkway formed by telescopic plates. In this solution speed variation is achieved by separating some transporting plates from others. The gap that is produced is covered by sheets that initially are concealed below the surface of the adjacent plate. A walkway with these features is described in patent document GB 2264686 A.        A variable speed walkway formed by parallelepipedic plates that move laterally in relation to each other. The speed variation is achieved by changing the operating direction, maintaining the projection of the speed on the embarking and disembarking direction constant. This walkway has a typical S shape. Walkways with these features described in patent documents U.S. Pat. No. 5,571,254 and EP 0646538 A2.        A variable speed walkway formed by a set of motorized and interconnected grooved rollers. The rollers have a small diameter, thus making the use surface approximately flat. The speed variation is achieved by making some rollers rotate quicker than others. In one variant of this walkway these rollers are only used in the acceleration and deceleration areas. The constant speed areas are solved with rubber belts similar to those currently used to transport people such as described in patent document FR 2747664 A1.        A variable speed walkway formed by a rubber belt that can be deformed. This continuous belt is capable of becoming longer in the central area and getting wider in the embarking and disembarking area, thus achieving the speed variation, as described in patent document EP 0831052 A1.        A variable speed walkway formed by many overlapping plates. The speed variation is obtained by moving some plates in relation to others, as described in patent documents GB 2025872 and P009902555.        
Specifically in this last patent, two types of plates or pallets having different lengths and alternately arranged are used as a moving surface of the walkway, each pair of pallets both being linked to each other according to an axis perpendicular to the operating direction.
The larger rear pallet is assembled on two lateral drive chains and on lateral drive guides, assuring perfect guiding for same, whereas the smaller front pallets have lateral rolling or sliding elements, moveable on the lateral guides of the rear pallet, such that both pallets undergo a relative longitudinal movement during the acceleration and deceleration phases.
This solution, perfectly valid from the theoretical point of view, has one drawback in practice since the shorter front pallet tends to be lifted due to any accidental cause that tends to lock both pallets during the relative movement thereof, which is dangerous for both the user and the mechanical system.
This can occur both by the accidental introduction of any small object between both pallets as well as by the deliberate lifting of the walkway on the part of the user.